Featuring Galileo's Handwritting. Galileo dedicated the manual for his engineering compass to young Cosimo II de Medici, whom he had tutored in mathematics the previous summer. Galileo had the instrument made in his own home, and supplemented his university income by teaching young gentlemen how to use it. The OU copy of Galileo's first and rarest printed book contains his own marginal notes, including corrections which were quickly incorporated into subsequent copies of the 1st printed edition. Observe how the fresh type cut deeply into the paper.